MESA, Ariz. -- Shelby Miller felt the pull of fatherhood as he trained at the Brewers' alternate training site in Appleton, Wis., early last season. With a newborn son at home and his place in Milwaukee's plans uncertain, Miller elected not to play.

Now with the Cubs, Miller is excited to pick up on a project he started shortly before making that decision last August. The veteran righty began working on a new slider while with the Brewers, and Miller got to test it out in his Cactus League debut on Monday against the Padres.

"I've never had something that was kind of nasty that people swung over the top of," Miller said on Tuesday morning in Arizona. "It used to always just be fastballs. I was a fastball pitcher. But to add that pitch is going to help me a ton, I think."

Once considered a rising rotation star, Miller is in camp with the Cubs on a Minor League deal as a veteran of eight seasons and a career's worth of setbacks. Over the 2017-19 seasons, the 30-year-old righty logged 82 total innings in the Majors, while working through a variety of injuries.

Miller saw Chicago as a great opportunity to continue his comeback, especially considering the team's need for starter innings in the season ahead. Miller does not project to be in the Opening Day rotation, but he could compete for a spot in the bullpen as a swing man or offer in-season depth.

"I'm coming in and trying to make an impression," Miller said. "Obviously, I was going to come in as a starter. And we signed some guys, some great arms that are obviously needed in this rotation. ... However I can help, I'd be more than willing to do."

In his outing against San Diego, Miller allowed a pair of hits to start things off, but then recovered with a strikeout of Tommy Pham (via the slider) before inducing a double play off the bat of Eric Hosmer. Cubs manager David Ross said it was a good test to see Miller work out of a jam out of the chute.

"What I liked the most is he got a little bit of traffic early on and pitched his way out of it," Ross said. "The slider depth was real -- some real swing and misses on the slider."

Tepera signed, bullpen moves

The Cubs finalized their one-year MLB contract with right-hander Ryan Tepera on Tuesday. That gives Chicago one more experienced veteran arm to throw into the setup mix ahead of closer Craig Kimbrel.

"There's so many pieces to that bullpen down there," Ross said recently. "He was a significant piece for us last year that kind of came in and got us out of big spots. He was able to handle the moment."

In order to vacate a spot on the 40-man roster for Tepera, the Cubs designated righty Duane Underwood Jr. (out of Minor League options) for assignment. Underwood, 26, had a 5.66 ERA with 27 strikeouts and six walks in 20 2/3 innings for Chicago last season, and his place in the Opening Day picture was unclear.

Also on Tuesday, the Cubs assigned righty Robert Stock to Triple-A Iowa after he cleared waivers. Stock will remain in camp as a non-roster invitee.

Worth noting

• The fact that Javier Báez, Kris Bryant and Anthony Rizzo are each in their contractual walk year will be a persistent storyline this year. Ross was asked Tuesday if their potential free agency could be a "rallying point" in a crucial campaign for both their future and the direction of the franchise.

"I see it more as these guys have committed to one another for a long time," Ross said. "And they're still committed to each other. I'm always under the impression, like, I'm OK with them being a little selfish this year. Sometimes you've got to take care of yourself and get your numbers. And if they all get their numbers, like we've said, I think we're going to be just fine."

• Righty Jake Arrieta faced hitters in a live batting-practice workout on Tuesday morning at the Cubs' complex. Arrieta is on a more conservative throwing program at the outset of camp, but should be due for his first Cactus League start in the coming days.

• Nico Hoerner, who is competing for the everyday job at second base for the Cubs, had a hard-hit double and single in Tuesday's 3-2 victory over the Royals.

• Center fielder Ian Happ served as the designated hitter in his spring debut on Tuesday and drew a walk in three plate appearances back in the leadoff spot.

Quotable

"It was nice. Other than the one guy in the upper deck who kept heckling our pitchers -- that was like the only guy you could hear. But, no, in all seriousness, it was fun to hear that stuff again. It was great to see fans." -- Ross, on having fans in the stands again

Up next

Right-hander Zach Davies, who was acquired from the Padres as part of the blockbuster trade that sent Yu Darvish to San Diego, is scheduled to make his Cubs debut on Wednesday. The Cubs will host the Mariners at 2:05 p.m. CT at Sloan Park (on ESPN and MLB.TV).